ThinkRail (JetBrains)

An Apache-2.0 agentic IDE built on the pi coding agent, with git-worktree isolation and living SPEC.md project knowledge.

What it is

ThinkRail is an agentic IDE from JetBrains, built as an incubator project around the pi coding agent. It wraps pi in a fuller interface: a workbench of editor tabs, a file tree with live git change marks, terminals, and several concurrent agent chats per workspace. Its central idea is isolation. You open a git repository as a project and cut workspaces from it as git worktrees, each with its own branch and working directory, so an agent can work without touching your main checkout. The project also keeps a graph of SPEC.md files beside the code, which the agent reads and updates through dedicated tools so intent persists across sessions. It ships as a native desktop app or as a thinkrail CLI that opens the same interface in a browser.

Key features

• Git-worktree workspaces, each with its own branch, so parallel agent work stays separate from your checkout
• Concurrent pi chat sessions per workspace, with live token and cost readouts and the ability to steer a running turn
• A SPEC.md graph maintained by the agent through spec tools, with a read-only Specs tree in the workbench
• MCP server support, where the app asks before calling tools a server does not mark read-only
• Provider access through JetBrains AI or pi's own auth, plus custom OpenAI-compatible model servers

Use cases

• Letting an agent try a change on a separate branch and merging only the result you want
• Running several agent tasks in parallel within one repository without them colliding
• Keeping design intent in project specs so later sessions start with context rather than rediscovering it
• Using a local or company model server, such as Ollama or vLLM, alongside hosted providers

Who it's for

Developers who already use pi or similar coding agents and want a richer interface for managing branches, chats, and project specs. It suits people comfortable with git worktrees and with agents that edit real repositories.

Getting started

Alternatives

The project directory lists related entries such as OpenCode, Aider, OpenHands, and Pi (earendil-works). These are only related directory entries, not endorsements or comparisons of capabilities.